This proposal requests funding through an Exploratory Development Grant for Mental Health Intervention Research. Panic disorder (PD) is a highly prevalent and debilitating condition. Research has suggested that cognitive-behavioral therapy (CBT) is a very effective treatment for PD with or without agoraphobia, however, a majority of patients with PD do not receive this type of therapy (or any recommended treatment). Some of the primary factors that limit patient participation in treatment include cost and treatment availability. Self-help treatments are a means to provide low-cost treatment to a much greater number of individuals, and available book-based self-help formats have been found to be effective. Interactive computer-based treatments offer additional advantages over a book-based approach because they are more engaging, thereby leading to greater compliance and decreased attrition. Moreover, computer treatments have the capacity to enhance learning through multiple modalities and interactive features. The purpose of the proposed investigation is to develop an interactive computer-administered version of the most recent genre of CBT treatments for panic disorder (treatment development phase) and to test the efficacy of this type of treatment relative to an established CBT bibliotherapy manual (pilot testing phase). The first phase of this proposal involves developing an interactive computer-based treatment that effectively emulates available CBT protocols for panic disorder. This development will involve translating manualized CBT interventions into a multimedia presentation with various interactive features designed to mimic the type of communication that typically occurs in live CBT. The second phase of this proposal involves refining the computer-administered treatment based on patient utilization from a small, representative sample of patients. Based on patient assessments, the treatment will be redesigned accordingly. The final phase of the proposal involves a clinical trial examining the relative efficacy of the refined computer treatment (about = 20) versus a book-based treatment (about = 20) and a delayed-treatment control group (about = 20). Outcomes will be compared at posttreatment and at 3-month follow-up. It is hypothesized that both active treatment groups will produce better outcomes relative to the control condition and that the computer-based treatment will produce superior outcomes relative to the book-based treatment.